Dental superstructure, and a method of manufacturing thereof

ABSTRACT

A dental superstructure, and a manufacturing method thereof, comprising a screw-channel ( 1 ), through which screw-channel a screw member is to be inserted, and a screw member seat ( 3 ), for providing support to the head of said screw member during fixation of said dental superstructure to a spacer element or an implant ( 5 ), are provided. Said dental superstructure is provided with a central axis of said screw-channel ( 1 ) and a central axis of said second mouth ( 4 ) that at least partly do not coincide. A manufacturing method thereof, a screw-member, and a screwdriver are also provided.

FIELD OF THE INVENTION

This invention pertains in general to the field of a dentalsuperstructure and a manufacturing method of said superstructure. Moreparticularly the invention relates to a superstructure to be connectedto an osseointegrated dental implant. A superstructure of this kind isdisclosed in SE506850.

BACKGROUND OF THE INVENTION

The goal of a dental implant system is to restore the patient to normalfunction, comfort, aesthetic, speech and health regardless of thecurrent oral condition. These implant systems are based on theimplantation of dental implants, such as dental implants made ofbiocompatible titanium, through insertion into the patient's jawbone. Inthis respect, the use of biocompatible titanium started in Sweden asearly as 1950, and has since then been further developed and spreadworld-wide. During the 1980's a number of implant systems entered theworld market. Methods are known in the art to attach a dentalsuperstructure to an implant. A couple of methods are based on the useof a screw member. Theses screw members can attach the superstructure tothe implant, either directly or via spacers.

When implants are implanted in the mouth of a patient who has beenwithout teeth for some time problems arise due to degeneration of bone.If a person has been without teeth for some time, the jawbone that isnot under strain of natural teeth or implants, will dissolve andassimilate over time, yielding less bone material for the properanchoring of a dental implant. To find enough bone for optimalimplantation, the implant has to be angled so that the general axis ofthe implant projects out of the mouth. Fixing a superstructure with ascrew member in a straight screw channel to such implants necessitatesthat the mouth of the screw channel may be forced to be placed on avisual surface of the dental superstructure. Also, the optimum placementof the implant, due to the present dental situation, often results in anon-optimum placement of the dental superstructure in terms of thepatient's aesthetics, phonetics and bite.

Therefore, there is a need in the dental field for greater freedom ofplacement of a dental implant in order to optimize the stability andsuccess of the implantation, while still achieving good aesthetics,phonetics and bite of the patient.

Furthermore, in the above mentioned dental situation there is a need tobe able to use an implant placed optimally with regard to the dentalsituation, that is, the anatomy of the jawbone, while still allowing thedental superstructure to be applied in an optimal way to said implant,such that the mouth of a screw channel not is visible from outside themouth of the patient.

The means already known in the art for achieving this goal include theuse of angled spacers and dental superstructures attached to the implantwith adhesive or with other techniques not based on the use of a screwmember. The angled spacers have many drawbacks and are characterized byadding significant height to the superstructure, multiple sources oferrors, since the coordination of multiple parts undoubtedly leads this,an unnecessarily high price, as a result of the multiple parts andmultiple manufacturing steps, increased risk of bacteriological attack,due to the several corners and surfaces exposable to this, weaker screwfor the attachment of the dental bridge, since no follow-up draft ofsaid screw is possible since a structure is applied on top of saidangled spacers. It also results in an increased complexity of theattachment of the superstructure to the implant. U.S. Pat. No. 6,848,908discloses an arrangement including an angled spacer element of thiskind, including a first passage and a second passage. The first passageis operative to fasten said spacer element in an implant, and the secondpassage is operative to fasten a superstructure on said spacer element.Superstructures attached to an implant without using a screw memberresults in less strength, difficulties in detachment and alsoincompatibility problems with commercially available implant systems oftoday.

Furthermore, U.S. Pat. No. 5,947,733 discloses a spacer element with anon-linear bore, connecting a first mouth, intended to be connected to adental implant, and a second mouth, intended to be connected to a dentalsuperstructure through a screw member engaging with the threaded part(132, 232, 332) of the spacer element. Thus, also this system is in needof spacer elements at least for solving the problem of guiding the mouthof a screw channel, such that it is not visible from outside the mouthof the patient.

There is therefore a need, among others, for a method of attaching ordetaching a dental superstructure to a dental implant at a chosen anglewithout adding additional height to the chosen superstructure.

Thus, there is a need for a new superstructure that may be fastened toan implant without angled spacer elements or superstructures attached tothe implant with only adhesive or with other techniques not based on theuse of a screw member. There is also need for a simpler, faster andcheaper production method of dental superstructures, while stillproviding the benefits according to above. Furthermore, there is a needto provide for the possibility of a simple assembly ex situ (outside thepatient's mouth) and application in situ (in the patient's mouth).

Hence, an improved superstructure, and a manufacturing method thereof,would be advantageous, and in particular a superstructure, and amanufacturing method thereof, allowing for the exclusion of angledspacer elements or fastening of a superstructure to an implant byadhesives, without being forced to place the mouth of the screw channelon a visual surface of the dental superstructure would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the present invention seeks to mitigate, alleviate oreliminate one or more of the above-identified deficiencies and toprovide an improved superstructure of the kind referred to, and amanufacturing method thereof. For this purpose the superstructure ofthis kind is characterized in that a central axis of at least one partof a screw-channel and a central axis of a mouth of a screw member seatdo not coincide, and the manufacturing method is characterized bydrilling a first bore from a first point of said superstructure, whichfirst point is intended to face an implant or spacer element, drilling asecond bore from a second point on said superstructure, which secondpoint is intended to provide a mouth of a screw channel for attachingsaid superstructure to said spacer element or implant.

Advantageous features of the invention are defined in the dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which the inventionis capable of will be apparent and elucidated from the followingdescription of embodiments of the present invention, reference beingmade to the accompanying drawings, in which

FIG. 1 illustrates a cross-section of an embodiment of a superstructureaccording to the present invention.

DESCRIPTION OF EMBODIMENTS

The following description focuses on embodiments of the presentinvention applicable to a superstructure, and also to a method ofmanufacturing said superstructure.

The present invention discloses, according to FIG. 1, a superstructure,and a manufacturing method thereof, comprising a main body, comprising ascrew-channel 1 with a first mouth 2, through which screw-channel 1 ascrew member is to be inserted, and a screw member seat 3 with a secondmouth 4, for providing support to the head of said screw member duringfixation of said dental superstructure to a spacer element or an implant5 through said second mouth 4, whereby a communication is obtainedbetween said first and second mouth, wherein at least one part of acentral axis of said screw-channel 1 differs from a central axis of saidsecond mouth 4. In this way the mouth 2 of the screw channel 1 may belocated such that the superstructure may be attached/detached to adental implant or a spacer element 5 where the mouth 2 of the screwchannel 1 not is visible from outside the patients mouth.

In one embodiment of the manufacturing method of said superstructure, asuperstructure is first manufactured in a way known to the skilledartisan, and then provided with a communication according to above. Sucha method is for example disclosed in the Swedish patent SE 509,437, butother manufacturing methods known to the skilled artisan, such asmoulding etc., are also within the scope of the present invention.

In one embodiment of the present invention the superstructure is, incontrast to the manufacturing methods according to the prior art,manufactured with integrated spacer elements, milled from onesingle-piece blank, such that the dental superstructure obtains a mainbody and spacer elements, wherein said main body and said spacerelements are integrated. In this context the term integrated means thatthe dental superstructure, comprising a main body, and the spacerelements are consisting of one piece of material, such that no interfaceis present in between said superstructure and said spacer elements. Inthis superstructure the dimensions of spacer elements can be varied inaccordance with the specific dental situation of a patient intended toreceive said replacement structure. When the superstructure is appliedthe spacer elements will be cooperating with dental implants, insertedand osseointegrated in bone tissue. To obtain a perfect fit, i.e. nogap, between the superstructure and the gum tissue, the length andangle, in respect of the jawbone, superstructure, and jawbone, of thespacer elements will be individual for each spacer in respective spacerposition.

In one embodiment the material of said superstructure may be selectedfrom the group comprising titanium, zirconium oxide, alloys of titaniumand zirconium, and other biocompatible materials, or combinationsthereof.

When a superstructure, according to any of the embodiments above, hasbeen obtained, a superstructure wherein a central axis of at least onepart of a screw-channel differs from a central axis of a mouth of ascrew member seat is provided. In one embodiment this is obtained,according to FIG. 2, by drilling a first straight bore 21 from a firstpoint 22 on a side of the dental superstructure, at which first point 22the mouth of the screw-channel is to be placed, and a second straightbore 23 from a second point 24 on the side of the dental superstructureintended to face the implant or spacer element. It is of course possibleto drill the second bore 23 before the drilling of the first bore 21,while still being inside the scope of the present invention. The firstand second bores are drilled such that they intersect in the interior ofthe dental superstructure. Then a third bore 31 may be drilled,according to FIG. 3, after the drilling of said first bore 21 and saidsecond bore 23. This third bore may result in a screw-channel. Thisthird bore may be drilled using said first and second bores as guides.Said third bore may be drilled by using a drill bit with a cuttingsurface of a sufficient diameter to create a bore through which a screwmember may be passed in order to attach the dental superstructure to aspacer element or an implant 5. The third bore 31, i.e. thescrew-channel 1, may preferably be drilled close to said second point24, but not the whole way through. Since the diameter of the third bore31 is larger than the diameter of said second bore 23, shoulders 32 willform in the screw-channel 1. Said shoulders may then form the seat 3 fora screw member head in the bottom of the screw-channel 1, while beingintegrated with said superstructure. Thus, a threaded part of a screwmember inserted in the screw-channel may be passed through said bore,i.e. said second bore 23, to subsequently attach the dentalsuperstructure to a spacer element or implant 5. Preferably, thediameter of said second bore 23 corresponds to the diameter of thethreaded part of the screw member, whereby the screw member may bepassed through said bore to fixate the superstructure to an implant or aspacer element 5. Thus, a dental superstructure comprising a main body,comprising a screw-channel 1 with a first mouth 2, through whichscrew-channel 1 a screw member is to be inserted, and a screw memberseat 3 with a second mouth 4, for providing support to the head of saidscrew member during fixation of said dental superstructure to a spacerelement or an implant 5 through said second mouth 4, may be obtained.Hereby a communication is obtained between said first mouth 2 and saidsecond mouth 4. By providing a central axis of at least a part of saidscrew-channel 1 and a central axis of said second mouth 4 that do notcoincide, one may guide the position of said first mouth 2, i.e. throughwhich a screw member is to be inserted, into a position that optimizesthe arrangement of the superstructure. This may for example be to locatesaid first mouth 2 in an aesthetically pleasing position, such as on asurface of the superstructure that can not be seen from outside themouth of the patient. It is also possible that only the direction of thecentral axis of a part of the screw-channel 1 differs from the directionof the central axis of the mouth 4 of the screw member seat 3, inaccordance with FIG. 1, while still being inside the scope of thepresent invention.

In one embodiment of the present invention the central axis of saidfirst mouth 2 and the central axis of said second mouth 4 do notcoincide.

In one embodiment the first bore 21 and the second bore 23 are made witha conventional twist drill. In this way the first bore 21 and the secondbore 23 are drilled to a diameter of a suitable size for passing of thethreaded part of a screw member, which screw member is used forattaching the superstructure to a spacer element or implant 5. It isalso possible to drill said second bore 23 using a drill bit with acutting surface of a sufficient diameter to create a bore through whicha screw member may be passed in order to attach the dentalsuperstructure to a spacer element or an implant.

It is also possible to drill said third bore all the way through saidfirst bore, in accordance with FIG. 4. Then a separate seat 41 for thescrew member head may subsequently be inserted and attached to saidsuperstructure. This may be done by attachment techniques known in theart, such as welding or attachment by known adhesive agents. It is evenpossible to only drill one bore, with a diameter through which a screwmember may be passed in order to attach the dental superstructure to aspacer element or an implant. This bore may extend all the way from saidfirst point 22 to said second point 24, or it may extend to a closeproximity to said second point 24. If said one bore extends all the wayfrom said first point 22 to said second point 24, a separate seat 41,comprising a hole 42 for matching the threaded part of a suitable screwmember, for the screw member head may subsequently be inserted andattached to said superstructure by attachment techniques known in theart, such as welding or attachment by known adhesive agents. If said onebore do not extend all the way from said first point 22 to said secondpoint 24, a bore, matching the threaded part of the screw member, may bedrilled from said first point 24, i.e. the point intended to face thedental implant or a spacer element 5, whereby the screw member seat 3and the second mouth 4 are created, according to the teachings above. Byproviding a central axis of at least a part of said one bore and acentral axis of said bore, matching the threaded part of thescrew-member, or said hole, for matching the threaded part of a suitablescrew-member, that do not coincide, one may guide the position of amouth of said one bore, i.e. through which a screw member is to beinserted, into a position that optimizes the arrangement of thesuperstructure.

An example of a separate seat 41 may be a ring with an outer diametercorresponding to the inner diameter of the screw-channel 1 of thesuperstructure, and an inner diameter corresponding to the threaded partof the screw member, intended to be used when fixating thesuperstructure to a spacer element or an implant 5.

In yet another embodiment of the present invention the superstructure isprovided with a dental implant seat or a spacer element seat, such as arecess suitable for receiving a protrusion on said dental implant orspacer element. It is of course also possible to provide thesuperstructure with a protrusion and the dental implant or spacerelement with a recess, as long as the seating effect is obtained. Thisdental implant seat or a spacer element seat provides the advantage ofeasier assembling of the superstructure on a dental implant or a spacerelement.

In one embodiment of the present invention the drill bit used, with acutting surface of a sufficient diameter to create a bore through whicha screw member may be passed, i.e. a screw-channel, such as the drillbit used when drilling said third bore, may have a declining cuttingsurface, such as an arched, semi-spherical, or spherical cuttingsurface. In this way the bottom part of the screw-channel may have adeclining shape, such as an arched or semi-spherical. Thus, the bottompart may fit with a screw member, according to FIG. 5, with a bevelled,such as arched, spherical or semi-spherical head 51 and a threaded part52. Hereby, the diameter of the screw member head 51 may decline, in anarched way, along with a surface 53 intended to, in use, bear upon theshoulders of a screw member seat, from the diameter of the screw memberhead 51 to approximately a diameter of a threaded part 52 of the screwmember. A screw member with a bevelled, such as arched, spherical orsemi-spherical, head may also follow a screw-channel 1 according to theinvention. The arched, spherical, or semi-spherical head of the screwmember may in this way act as a guide for guiding the screw member fromthe mouth 2 of screw-channel, i.e. said first point 22, to a seat 3 inthe bottom of said screw-channel 1. This seat also comprises said secondbore 23, through which the threaded part of the screw member may bepassed to attach said superstructure to a spacer element or implant 5.The screw member with a spherical or semi-spherical head 51 alsoprovides a higher fixing strength and self-centring properties. Sincethe surface 53 bearing on the shoulders of the screw member seat 3 isarched, such as spherical or semi-spherical, a greater contact surfacebetween the screw member and the shoulders 32 of the screw member seat 3is obtained. Thereby, the fixating strength obtained from the fixationof the superstructure to the dental implant 5 may be greater than if thesurface bearing on the shoulders of the screw member not was arched. Thescrew member is provided with a recess for receiving a driving means,such as a screwdriver. This recess may be a score, or a slit. The recessmay also have other shapes, corresponding to a screwdriver, such as astarshape or a recess with a number of sides, such as tri-, tetra-,penta-, or hexagonal. It is of course within the present invention toprovide such a recess in any other shapes corresponding to a matchingmale part on a screwdriver or other driving means. Thus, a screw-member,comprising a threaded part and a screw-head with a recess for receivinga driving means, such as a screwdriver, said screw-head comprising asurface bearing, in use, on shoulders of a screw-member seat, whereinsaid surface is bevelled towards the threaded part, has been described.

It is also within the present invention to drill said third bore withdrilled bits having cutting surfaces with other declining and/orbevelled shapes, such as cone shaped.

The screw member may be fixed with a screwdriver, in accordance withFIG. 6 a, comprising a rotatable handle portion 61 and a flexible and/orbendable shaft portion 62, with a distal end 63 coupled to said handleportion 61 and a proximal end 64 coupled to a tip 65 for driving saidscrew member with rotation transmitted from said rotatable handleportion 61. Such a screwdriver, for fastening screw members in ascrew-channel described above, may comprise a flexible and/or bendableshaft 62. This flexible shaft 62 may in one embodiment comprise twinnedwires 66, giving a high torque capacity, independent of shaft bendingand angle to the screw member. Said flexible shaft portion 62 maycomprise a plurality of wires 66, said wires being twinned in aplurality of layers, in accordance with FIG. 6 b, such that saidflexible shaft 62 is formed between said distal end 63 and said proximalend 64. The plurality of layers may be twinned such that one part of thelayers is twinned in one direction while the other part of the layers istwinned in the other direction. Since said screwdriver has twinnedlayers of wires, in accordance with FIG. 6 b, in two directions thescrewdriver is provided with torque capacity in both rotationaldirections of said flexible shaft. In one embodiment the number oftwinned layers may be uneven, whereby the uneven number of layers aretwinned in a direction giving the screwdriver a unfastening torquecapacity while the even number of layers are twinned in a directiongiving the screwdriver a fastening torque capacity. The number of layersmay for example be selected within the interval of 2 to 30, such as 10to 20, but this interval is only intended to be interpreted as guidanceand not as limiting. Of course, it is possible to construct screwdriverswith a number of twinned layers outside the given interval, which stillmay obtain the intended effect. The torque capacity of such ascrewdriver may be at least 30 to 35 Ncm.

In one embodiment the screwdriver is provided with a flexible and/orbendable core, in accordance with FIG. 6 c, in said shaft, onto whichthe plurality of wires are twinned. This flexible and/or bendable coremay for example be manufactured of an ordinary plastics or rubber,fulfilling the desired features according to flexing and/or bending inrespect of being able to flexate or bend in the screw channel.

In one embodiment the rotatable handle portion 61 and a flexible and/orbendable shaft portion 62 of the screwdriver are separable. In thisembodiment the flexible and/or bendable shaft portion 62 may first beinserted in the screw-channel 1, and thereafter the rotatable handleportion 61 is mounted and fixed to said flexible and/or bendable shaftportion 62. Thereby, it may be easier to access the screw member in thescrew-channel 1, if the central axis of the screw-channel and thecentral axis of the second mouth differs in a high degree.

The elements and components of an embodiment of the invention may bephysically, functionally and logically implemented in any suitable way.Indeed, the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, theinvention may be implemented in a single unit, or may be physically andfunctionally distributed between different units and processors.

Although the present invention has been described above with referenceto specific illustrative embodiments, it is not intended to be limitedto the specific form set forth herein. Rather, the invention is limitedonly by the accompanying claims and other embodiments than the specificabove are equally possible within the scope of these appended claims.

In the claims, the term “comprises/comprising” does not exclude thepresence of other elements or steps. Furthermore, although individuallylisted, a plurality of means, elements or method steps may beimplemented by e.g. a single unit or processor. Additionally, althoughindividual features may be included in different claims, these maypossibly advantageously be combined, and the inclusion in differentclaims does not imply that a combination of features is not feasibleand/or advantageous. In addition, singular references do not exclude aplurality. The terms “a”, “an”, “first”, “second” etc do not preclude aplurality. Reference signs in the claims are provided merely as aclarifying example and shall not be construed as limiting the scope ofthe claims in any way.

1. A dental superstructure comprising a screw-channel with a firstmouth, through which screw-channel a screw member is to be inserted, anda screw member seat with a second mouth, for providing support to thehead of said screw member during fixation of said dental superstructureto a spacer element or an implant through said second mouth, whereby acommunication is obtained between said first mouth and said secondmouth, wherein at least one part of a central axis of said screw channeland a central axis of said second mouth do not coincide.
 2. The dentalsuperstructure according to claim 1, wherein said screw member seat isintegrated with said dental superstructure.
 3. The dental superstructureaccording to claim 1, wherein shoulders of said screw member seat has adeclining shape.
 4. The dental superstructure according to claim 1,wherein shoulders of said screw member seat has an arched orsemi-spherical shape.
 5. The dental superstructure according to claim 1,wherein said superstructure is manufactured of a material selected fromtitanium, zirconium oxide, alloys of titanium and zirconium.
 6. A methodof manufacturing of a dental superstructure comprising a screw-channelwith a first mouth, through which screw-channel a screw member is to beinserted, and a screw member seat with a second mouth, for providingsupport to the head of said screw member during fixation of said dentalsuperstructure to a spacer element or an implant, whereby acommunication is formed between said first mouth and said second mouth,wherein drilling said communication such that at least one part of acentral axis of said screw-channel and a central axis of said secondmouth do not coincide.
 7. The method according to claim 6, wherein saiddrilling comprises a drilling of a first straight bore from a firstpoint, and a drilling of a second straight bore from a second point,such that said first bore and said second bore intersect in the interiorof said superstructure to form said communication.
 8. The methodaccording to claim 7, wherein the drilling of said first bore and saidsecond bore is done by a twist drill, whereby a diameter suitable forconstituting the threaded part of a screw member is obtained.
 9. Themethod according to claim 7, wherein said drilling comprises a drillingof a third bore using said first bore and said second bore as guides,said third bore being drilled by using a drill bit with a cuttingsurface of a sufficient diameter to create said screw-channel throughwhich said screw member may be passed in order to attach said dentalsuperstructure to said spacer element or said implant.
 10. Ascrew-member, comprising a threaded part and a screw-head with a recessfor receiving a driving means, said screw-head comprising a surface,bearing, in use, on shoulders of a screw-member seat, wherein saidsurface is bevelled towards said threaded part.
 11. A screwdriver,comprising a rotatable handle portion and a flexible shaft portion, witha distal end coupled to said handle portion and a proximal end coupledto a tip for driving a screw member with rotation transmitted from saidrotatable handle portion, wherein by said flexible shaft portioncomprising a plurality of wires, said wires being twinned in a pluralityof layers, such that said flexible shaft portion is formed between saiddistal end and said proximal end.
 12. A screwdriver according to claim11, wherein one part of said plurality of layers is twinned in onedirection and another part of said plurality of layers is twinned inanother direction.